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UND 363 Alk Congo Re
UND 363 Alkaline Congo Red
| Question | Answer |
|---|---|
| Purpose of Alkaline Congo Red | demonstrate amyloid |
| principle of Alkaline Congo Red | congo red is linear molecule which allows for hydrogen bonding of the AZO and Amine groups of Amyloid |
| What is an underlying technique of Alkaline Congo Red per pretreatment w/ alkaloid | alkaloid pretreatment to release native internal hydrogen bonds between protein chains and therefore more sites for dye binding |
| fixatives of Alkaline Congo Red | Alcohol, or carnoy PREFERRED, but 10% NBF , bouins, zenkers are OK. ***Prolonged storaged in 10%NBF will decrease staining*** |
| thickness and why | 8-10microns, if not at this thickness the applegreen birefringence will not show |
| explain the specificity of the control for this stain | the control need to be known (one that has been shown to contain amyloid) |
| explain some caveats with the control slides | keep minimal on hand (increased age will decrease stain intensity), ALSO large deposits give less intense stain reaction than new small deposits |
| microscope of Alkaline Congo Red | light and polarized scope (to ID amyloid) |
| what are the 3 major reagents of Alkaline Congo Red | harris hematox - stains nuclei, alkaline salt soln' - releases hydrogen bonds, congo red- has AZO and amine groups that form hydrogen bonds with hydroxyl radicals of amyloid |
| typical results of Alkaline Congo Red | amyloid - deep pink to red (light microscope)/apple green (w/ polarized microscope) elastic - pale pink (light micro) nuclei- blue |
| explain why congo red is better than other methods to remove false positives | other methods can create false positive (and false birefringment) due to excess dye retained in tissue ***congo red will not give false pos. when done CORRECTLY |
| what components help give a clean background with congo red | sodium chloride and high alcohol found in dye solvent depress dye ionization and acid based staining resulting in stained section with clean background |
| name to components of the stain that are extremely important | saturation of solution is extremely important, and the thickness (ie too thin = faint red, too thick and you get yellow birefringence) |
Created by:
mustangvxd
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